1. Field of the Invention
The present invention relates to a flexible sheet of insulation material placed in a portable cooler for improving the insulation of perishables and the effectiveness of the cooling medium placed in the cooler.
2. Description of the Prior Art
Insulation of storage containers has resulted in numerous prior art inventions. Most of these are directed to containers of constant geometry. That is, floor, walls, and top are provided, defining an outer boundary, which remains constant with respect to the constituent boundary members regardless of the volume of the contents. Generally, material having superior insulation characteristics is incorporated into one or more boundary members.
U.S. Pat. No. 5,154,309, issued to Henry Wischusen III et al. on Oct. 13, 1992, describes an insulated shipping container which is intended to preserve perishables, such as seafood, with a cooling medium, such as ice. One element of the container is a U-shaped insulating blanket made from several strata of insulating material. This blanket, when the container is assembled, is sandwiched between inner and outer walls of other components, and improves insulation by preventing transfer of heat by conduction and convection. It should be noted that this blanket always bears against or is located immediately beneath a top wall member of the container.
Another shipping container is seen in U.S. Pat. No. 5,105,970, issued to Thomas G. Malone et al. on Apr. 21, 1992. An insulation member is made from a plural ply including a ply of polyethylene foam. The insulation member occupies a constant location within the container.
U.S. Pat. No. 5,022,101, issued to Jeffrey E. Gosselin et al. on Jun. 11, 1991, illustrates a thermal cover place over a spa. The cover is formed by a three ply lamination including a plastic film. Another cover is seen in U.S. Pat. No. 4,972,529, issued to Sidney K. Wolfson, Jr., on Nov. 27, 1990. This cover is made from, preferably, two plies of a plastic such as polypropylene.
U.S. Pat. No. 4,759,467, issued to Thomas R. Byrne on Jul. 26, 1988, discloses a liner for a cooler which prevents water originating from melted ice from commingling with perishables stored in the cooler. The liner has a floor, lateral walls, and an open top. Preferred constituent materials include extruded film of polyvinyl chloride, polyethylene, and the like.
A thermal insulating blanket for sealing an opening in a building is shown in U.S. Pat. No. 4,675,225, issued to William P. Cutler on Jun. 23, 1987. The blanket described therein is fiber filled and compressible, the interior communicating with the exterior, so that the fiber filling can be compressed and expanded.
The use of polyurethane in a blanket is seen in U.S. Pat. No. 4,944,844, issued to Joseph J. Marcinko on Jul. 31, 1990. The polyurethane is reinforced by synthetic fibers, and is not employed for insulation purposes.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.